Various safety apparatuses are used and to which roof workers can be attached to arrest the fall of a worker off the roof. Many of these devices are used for pitch roofs and wherein the worker is fitted with a harness to which a safety line with an energy absorbing locking mechanism is secured and attached to the device. The safety apparatus is usually retained on the roof by fasteners secured into the roof at a predetermined location. When there is a need to work in different areas of a roof, some of these apparatus require to be disconnected from the roof and reconnected at a different location. These fasteners damage the roof and require repair to prevent leakage. Also, the displacement of these apparatuses is time-consuming and poses a danger in that during the relocation of the apparatus the workers are not protected by the safety lines as they are connected to the safety apparatus which is disconnected from the roof. It is also known to use mobile vehicles when working on flat roofs and to which the workers are attached. However, these vehicles are supported on wheels and when a sudden pulling force is applied to the vehicle by a worker falling off a roof, the vehicle can be displaced on the roof thereby providing extra length in the safety line connected to the worker which may cause serious injury or death to the worker. It is not a fail-proof device, although it resolves the problem of being displaceable and not having to puncture the roof for securement of the device. Working on roofs is a dangerous occupation.